Aseptic loosening of the acetabular cup in total hip replacement (THR) remains a major problem. Current diagnostic imaging techniques are ineffective at detecting early loosening, especially for the acetabular component. The aim of this preliminary study was to assess the viability of using a vibration analysis technique to accurately detect acetabular component loosening. A simplified acetabular model was constructed using a Sawbones foam block into which an acetabular cup was fitted. Different levels of loosening were simulated by the interposition of thin layer of silicon between the acetabular component and the Sawbones block. This included a simulation of a secure (stable) fixation and various combinations of cup zone loosening. A constant amplitude sinusoidal excitation with a sweep range of 100–1500 Hz was used. Output vibration from the model was measured using an accelerometer and an ultrasound probe. Loosening was determined from output signal features such as the number and relative strength of the observed harmonic frequencies.Introduction
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